The International Olympic Committee says it remains confident the upcoming Winter Games in Sochi will be “safe and secure” despite terrorist bombings in the Russian city of Volgograd that have killed more than 30 people.

The IOC says its president, Thomas Bach, has written to Russian President Vladimir Putin expressing condolences for the Volgograd attacks and stating that he remains "certain that everything will be done to ensure the security of the athletes and all the participants of the Olympic Games."

Suicide Bombings in Volgograd, Russia

Monday, a suspected suicide attack demolished a crowded trolley bus in Volgograd, some 650 kilometers northeast of Sochi, which will host the 2014 Winter Olympics in February. The attack came one day after a deadly suicide bombing at the city’s main railway station.

Russian authorities have increased security in and around the southern city.

A spokesman for Russia's main investigative agency says the bomb in Monday's explosion was similar to the one used in Sunday's attack, confirming suspicions that they may be linked.

There was no immediate claim of responsibility for either blast, but Islamist insurgents from the nearby North Caucasus region have carried out similar attacks on public transit targets in Russia in recent years.

“Attacking the Sochi Olympics itself would be the ‘Holy Grail’ for one of these terrorist groups,” said Andrew Kuchins, who directs the Russia and Eurasia Program at the Center for Strategic and International Studies in Washington.

He said, “Sochi has been virtually under lockdown for the last six months or so. Being able to penetrate that security is not going to be easy. So perhaps we see a strategy of individuals and groups undertaking terrorist acts in other parts of Russia.”

Kutchins predicts fear gripping Volgograd will spread. He said, “The creation of a sense of terror around the country is already developing. I am afraid it is going to be a very precarious and dangerous time between now and the games.”

Putin has ordered Russia’s counterterrorism agency to step up security in Volgograd and elsewhere.

Sowing fear

Anatoly Ermolin, a veteran of Russia's special security forces, told VOA's Russian Service that what happened in Volgograd was a planned terrorist act and carried out professionally. He says it is a "layered attack" which may not be over, adding that the goal was to have the whole country talking about it in the lead-up to New Years celebrations.

U.S. National Security Council spokesperson Caitlin Hayden condemned the attacks in Russia, saying the United States stands with the Russian people against terrorism. Hayden's statement says the U.S. government has offered its full support to the Russian government in security preparations for the upcoming Games.

Russia has introduced some of the most stringent security at any international sporting event, including a limited-access security cordon around the entire city of Sochi and requiring spectators to have accreditation documents that include passport details and contact information.

Authorities initially said Sunday's blast was set off by a female suicide bomber from Dagestan - a republic in the nearby volatile North Caucasus. But authorities later said they believe the attacker was a man.

Targeting civilians

An attack in Volgograd by a female suicide bomber on October 21 killed five people and wounded 30. Investigators also identified her as coming from Dagestan.

Dagestan is one of the centers of an ongoing Islamist insurgency in the North Caucasus.

In early July, the leader of the Islamist insurgency in the North Caucasus, Doku Umarov, declared an end to a moratorium on attacks on Russian civilian targets that he had announced the previous year.